1. Field of the Invention
This invention relates generally to methods and systems for expanding the amount of video information which is be transmitted within a given bandwidth, and more particularly, to a system whereby two video channels are compressed and transmitted within a standard video channel.
2. Description of the Related Art
There are numerous applications in video transmission systems where it would be advantageous to transmit multiple programs on channels presently designated for a single program. Many attempts are currently being made using digital techniques to achieve this objective. Digital techniques are, however, very expensive at both, the transmitting and receiving ends. In addition, the application of known digital techniques results in the introduction of objectionable artifacts and a degradation of picture quality.
There is, therefore, a need for a video transmission arrangement wherein a plurality of video programs are compressed into a single video channel, without significant degradation of the video picture. In addition, it is highly desirable that the multi-program single channel have the capacity to be scrambled to ensure that the video information can be accessed only by authorized viewers.
It is, therefore, an object of this invention to provide a system for transmitting two video programs in one video channel.
It is another object of this invention to provide a system for compressing two video signals corresponding to respective video programs into a standard video channel using conventional carrier frequencies.
It is also an object of this invention to provide a system for transmitting two video programs in one video channel wherein the video picture quality of either video program is not degraded below that of commercially acceptable non-broadcast video media.
It is a further object of this invention to provide a system for compressing two video programs into one video channel, wherein decompression circuitry is easily incorporated in conventional television tuners.
It is additionally an object of this invention to provide a system for transmitting two video programs in one video channel without adversely affecting the audio carrier.
It is yet a further object of this invention to provide an encoder arrangement wherein two video programs are combined into a single video channel.
It is also another object of this invention to provide a decoder arrangement wherein two video programs are extracted from a single video channel.
It is yet an additional object of this invention to provide an encoder arrangement wherein two video signals corresponding to respective video programs are compressed into a single video channel.
It is still another object of this invention to provide a decoder arrangement wherein a compressed video signal in a single video channel is decompressed into two video programs.
It is a yet further object of this invention to provide a system wherein two video programs are compressed into a single video channel in accordance with a predetermined scrambling arrangement whereby neither video program is viewable without authorization.
It is also a further object of this invention to provide a system wherein two video programs are compressed into a single video channel in accordance with a scrambling arrangement which is changeable on a frequent basis to enhance security from unauthorized viewing.
It is additionally another object of this invention to provide a system wherein two video programs are compressed into a single video channel in accordance with a scrambling arrangement, and wherein changeable scrambling data is transmitted with the single video channel for facilitating descrambling at a receiver of the single video channel.